Make tests run faster by doing intake_server fixture per module not per function

[danielballan]

The tests run slowly right now because each tests stand up a fresh intake_server fixture, which involves starting up a Tornado server. A separate server per test has advantages---it ensures that tests don't mutually interfere via persisted state on the server---and it probably makes sense for intake tests to take that approach.

But if we can assume that the intake server itself it working, I think it is safe to set up one server per module rather than one server per test. My guess is that this would reduce the test time by ~100X and make development much nicer.

[danielballan]

Closed by #60